If the HP Proliant N40L did not fulfill you need for speed in a pint-size form factor, then check out the Fujitsu Primergy MX130 S2 micro server which is much more expensive than HP’s device but also way more powerful.
The server comes with an AMD Opteron 3250 CPU clocked at 2.5GHz plus 4GB of RAM, two 500GB hard disk drive, a PSU with an 85 per cent efficiency, GbE capabilities (via a BCM57780 chip), an AMD880G chipset (with an ATI Radeon HD 4250 GPU) plus three fans in a microtower chassis with a 13L volume.
It can take up to 16GB DDR3 ECC RAM (thanks to four memory slots) as well as up to four 3.5in hard disk drives (that’s up to 16TB of storage) and up to six 2.5in HDDs (that’s up to 6TB of storage).
Expansion and connectivity options include 12 USB ports (two front, six back and four internal), a dual-link DVI port, audio in/out, a serial port, two PS2 ones, a GbE connector, six SATA ports with RAID 1/0/10 compatibility, four low profile slots (x1, x16, x4 and normal PCI) and a 5.25in external drive bay.
Note that the Primergy MX130 S2 doesn’t have hot-plug capabilities.